I think the right way forward with this is to meet with His parents only....... and explain the situation with your parents, your inactivity with the JW religion the possibility of being shunned etc.
Why you chose to fade in hopes that you can keep a relationship with your family intact.
Describe the attitude about dating outside the religion and the restraints on your father as an Elder.
As always, Pete Zahut comes up with a great idea ie showing them family photos to demonstrate that you do have a family. If you indeed eventually marry you will have a legal position that even your Elder father will have to accept.